Rotate vector reducer design using resnet-based model and integration of discretized optimization

Jiacheng Miao,Chaoyang Li,Xing Du,Bingkui Chen 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.4

The author present an artificial intelligent (AI)-based deep generative model that demonstrate how to generate design options of mechanical systems, which are not only suitable for specific working conditions but also optimized for engineering performance. In current study, (1) a structural generative residual netowork (SG-Resnet) model is developed to establish the non-linear mapping between the working conditions and the external dimensions of the reducer, the main hyperparameters influencing the prediction ability and learning rate of the SG-Resnet are analyzed. (2) The mixed population non dominated sorting genetic algorithm-II (MP-NSGA-II) is proposed, and used to obtain pareto optimal solutions of the internal dimensions of the reducer. Experiments are performed to validate the positive effect of the structural generative model on the stiffness of the reducer. This research provides a novel method for reducer design and lays a solid foundation for the development of sequential engineering software for integrated rotate vector (RV) reducer.

Robust Observer-based Trajectory Tracking Control for Unmanned Aerial Manipulator

Jiacheng Liang,Yanjie Chen,Ningbin Lai,Bingwei He 제어·로봇·시스템학회 2023 International Journal of Control, Automation, and Vol.21 No.2

This paper aims at the stable motion control problem of the unmanned aerial manipulator (UAM) with internal interactions and external environment disturbances, and proposes a robust observer-based trajectory tracking control framework. Considering the large-dimensional nonlinearity and underactuated of UAM dynamics, a separate control scheme is adopted, including a geometric controller for quadrotor UAV and prescribed performance control (PPC) method for onboard active manipulator (OAM). In particular, an observer-based geometric control scheme is developed for the position and attitude tracking of the quadrotor UAV to ensure steady flight, where the quadrotor UAV attitude is represented by the rotation matrix to eliminate singularities or ambiguities. Subsequently, an observer-based PPC method is presented for the OAM to guarantee the prescribed transient and steady-state performance responses. Finally, the simulation comparisons and experimental study validate the effectiveness and performances of the proposed control framework.

Distributed Formation Control of Quadrotor UAVs Based on Rotation Matrices without Linear Velocity Feedback

Yanjie Chen,Jiacheng Liang,Zhiqiang Miao,Yaonan Wang 제어·로봇·시스템학회 2021 International Journal of Control, Automation, and Vol.19 No.10

This paper considers the problem of the formation control for multiple underactuated quadrotor UAVs without linear velocity measurements. The objective of this paper is expected to realize smooth formation performances for a quadrotor group. A distributed formation controller is designed directly using rotation matrices to obviate the singularities associated with the Euler-angles or the ambiguity of quaternions. A two-step procedure isadopted for the control development after transforming the dynamics of each quadrotor into a new form. At first, an intermediary control variable is introduced to achieve the formation control, where some auxiliary systems are designed in the presence of lacking linear velocity measurements. Then, based on the thrust force and reference angular velocity decoded from the intermediary control variable, the torque input of each quadrotor is proposed for angular velocity tracking. The case of formation control with a virtual leader is also investigated, where at least one quadrotor has the information of the leader. The asymptotic stability of the proposed control system is analyzed by Lyapunov-like tools, and the effectiveness of the proposed control method is verified by simulation studies. Thesimulation results show that the proposed method can guide the quadrotor group to form the desired formation smoothly without linear velocity feedback, which has great potentials for the UAV group to execute the challenging mission in hostile environments.

A dynamic multi-objective evolutionary algorithm based on prediction

Wu Fei,Chen Jiacheng,Wang Wanliang 한국CDE학회 2023 Journal of computational design and engineering Vol.10 No.1

The dynamic multi-objective optimization problem (DMOP) is a common problem in optimization problems; the main reasons are the objective’s conflict and environment changes. In this paper, we provide a prediction approach based on diversity screening and special point prediction (DSSP) to tackle the dynamic optimization issue. First, we introduce a decision variable clustering and screening strategy that clusters the decision space of the non-dominated solution set to find the cluster centroids and then employs a decision variable screening strategy to filter out solutions that have an impact on the distribution of individuals. This approach can broaden the range of dynamic multi-objective optimization algorithms. Second, an approach for predicting special points is suggested. The algorithm’s convergence is improved following environmental changes by forecasting the special point tracking Pareto front in the object space. Finally, the forward-looking center points are used to predict the non-dominated solution set and eliminate the useless individuals in the population. The prediction strategy can help the solution set converge while maintaining its diversity, which is compared with the four other state-of-the-art strategies. Our experimental results demonstrate that the proposed algorithm, DSSP, can effectively tackle DMOPs.

Theoretical models of threshold stress intensity factor and critical hydride length for delayed hydride cracking considering thermal stresses

Jingyu Zhang,Jiacheng Zhu,Shurong Ding,Liang Chen,Wenjie Li,Hua Pang 한국원자력학회 2018 Nuclear Engineering and Technology Vol.50 No.7

Delayed hydride cracking (DHC) is an important failure mechanism for Zircaloy tubes in the demandingenvironment of nuclear reactors. The threshold stress intensity factor, KIH, and critical hydride length, lC ,are important parameters to evaluate DHC. Theoretical models of them are developed for Zircaloy tubesundergoing non-homogenous temperature loading, with new stress distributions ahead of the crack tipand thermal stresses involved. A new stress distribution in the plastic zone ahead of the crack tip isproposed according to the fracture mechanics theory of second-order estimate of plastic zone size. Thedeveloped models with fewer fitting parameters are validated with the experimental results for KIH andlC. The research results for radial cracking cases indicate that a better agreement for KIH can be achieved;the negative axial thermal stresses can lessen KIH and enlarge the critical hydride length, so its effectshould be considered in the safety evaluation and constraint design for fuel rods; the critical hydridelength lC changes slightly in a certain range of stress intensity factors, which interprets the phenomenonthat the DHC velocity varies slowly in the steady crack growth stage. Besides, the sensitivity analysis ofmodel parameters demonstrates that an increase in yield strength of zircaloy will result in a decrease inthe critical hydride length lC , and KIH will firstly decrease and then have a trend to increase with the yieldstrength of Zircaloy; higher fracture strength of hydrided zircaloy will lead to very high values ofthreshold stress intensity factor and critical hydride length at higher temperatures, which might be themain mechanism of crack arrest for some Zircaloy materials

Synthesis of Porous NiMo Sulfide Microspheres for High-Performance Dye-Sensitized Solar Cells and Supercapacitor

Wen Yang,Bin Xia,Jiacheng Lu,Peizhi Yang,Xiaobo Chen 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2019 NANO Vol.14 No.4

"Novel hierarchical porous NiMoS4 microspheres with high electrochemical performance was successfully prepared using a facile one-step hydrothermal method. The dual application of porous NiMoS4 microspheres in energy harvesting and storage (i.e., dye-sensitized solar cells (DSSCs) and supercapacitors (SCs), respectively) is explored. In contrast to NiS2 nanosheets, MoS2 nanosheets and Pt counter electrodes (CEs), the NiMoS4 microspheres CE demonstrated the lowest charge transfer resistance and highest electrocatalytic activity for the I3 - /I - redox couple reaction. The NiMoS4-based DSSC showed a higher power conversion efficiency (8.9%) even than that of Pt-based DSSC (8.7%) under simulated standard global AM 1.5G sunlight (100 mW cm -2). As an electroactive material for SCs, the assembled NiMoS4//AC asymmetric supercapacitor showed excellent specific capacitance (118.7 F g -1 at 1 Ag -1), high energy density of 42.2 Wh kg -1 (with a power density of 799.2 W kg -1), and superior cycling durability with a specific capacitance retention of 79.5% after 9000 cycles at 3 A g -1."

An LED SAHP-based Planar Projection PTCDV-hop Location Algorithm

( Yuexia Zhang ),( Hang Chen ),( Jiacheng Jin ) 한국인터넷정보학회 2019 KSII Transactions on Internet and Information Syst Vol.13 No.9

This paper proposes a planar projection DV-hop location algorithm (PTCDV-hop) based on the LED semi-angle at half power (SAHP, which accounts for LED SAHP characteristics in visible light communication (VLC)) and uses the DV-hop algorithm for range-free localization. Distances between source nodes and nodes positioned in three-dimensional indoor space are projected onto a two-dimensional plane to reduce complexity. Circles are structured by assigning source nodes (projected onto the horizontal plane of the assigned nodes) to be centers and the projection distances as radii. The proposed PTCDV-hop algorithm then determines the position of node location coordinates using the trilateral-weighted-centroid algorithm. Simulation results show localization errors of the proposed algorithm are on the order of magnitude of a millimeter when three sources are used. The PTCDV-hop algorithm has higher positioning accuracy and stronger dominance than the traditional DV-hop algorithm.

Surface Centroid TOA Location Algorithm for VLC System

( Yuexia Zhang ),( Hang Chen ),( Shuang Chen ),( Jiacheng Jin ) 한국인터넷정보학회 2019 KSII Transactions on Internet and Information Syst Vol.13 No.1

The demand for indoor positioning is increasing day by day. However, the widely used positioning methods today cannot satisfy the requirements of the indoor environment in terms of the positioning accuracy and deployment cost. In the existing research domain, the localization algorithm based on three-dimensional space is less accurate, and its robustness is not high. Visible light communication technology (VLC) combines lighting and positioning to reduce the cost of equipment deployment and improve the positioning accuracy. Further, it has become a popular research topic for telecommunication and positioning in the indoor environment. This paper proposes a surface centroid TOA localization algorithm based on the VLC system. The algorithm uses the multiple solutions estimated by the trilateration method to form the intersecting planes of the spheres. Then, it centers the centroid of the surface area as the position of the unknown node. Simulation results show that compared with the traditional TOA positioning algorithm, the average positioning error of the surface centroid TOA algorithm is reduced by 0.3243 cm and the positioning accuracy is improved by 45%. Therefore, the proposed algorithm has better positioning accuracy than the traditional TOA positioning algorithm, and has certain application value.

Effects of Heating Temperature on Charge/Discharge Characteristics of TiO₂-TiN/MoO₂-MoO₃ Composite Films on Ti as High-Safety LIB Anode

Kohya Matsuhira,Song-Zhu Kure-Chu,Xuewen Chen,Jiacheng Liu,Noriaki Kurita 한국표면공학회 2023 한국표면공학회 학술발표회 초록집 Vol.2023 No.11-1